Air filter with pathogen monitoring and inactivation

ABSTRACT

An improved technology for inactivation of viruses, for example the SARS-CoV-2 virus that is causing the Covid-19 pandemic, is described. The technology can include a device that includes a substrate coated in a polymer that is infused with a pathogen inactivating material. In various embodiments, at a given time, a portion of the pathogen inactivating material is exposed to the environment, and the device is configured to periodically or intermittently expose additional pathogen inactivating material to the environment. For example, the polymer can be ablative or sacrificial.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to U.S. ProvisionalPatent Application No. 63/107,388 entitled “Air Filter with PathogenMonitoring and Inactivation,” filed on Oct. 29, 2020 and U.S.Provisional Patent Application No. 63/252,514 entitled “Air Filter withPathogen Monitoring and Inactivation,” filed on Oct. 5, 2021, thecontents of both of which are incorporated by reference herein in theirentirety.

TECHNICAL FIELD

The present invention generally relates to pathogen inactivating agentsand, more particularly, to pathogen inactivating agents infused within apolymer in a manner such that additional pathogen inactivating materialis periodically or intermittently exposed to the environment.

BACKGROUND

Air filters for HVAC systems provide excellent filtration of particles.Depending upon the rating of the filter, smaller and smaller particlesmay be filtered out of the air. A specific type of filter, highefficiency particulate air (HEPA) filter, is utilized to filter micronand submicron particles from the air.

While very fine particle filters offer trapping of allergens and otherproblem materials such as fine dust, all of these passive air filters donot allow for the inactivation of pathogens that may be borne by the airas it flows through the HVAC system. HEPA filters may also cause a highpressure drop across the filter, resulting in poor airflow through theHVAC system.

Thus, there is therefore a need for a long-lasting, pathogeninactivating, and high percentage capture air filter for HVAC systems.

SUMMARY

The embodiment is the use of air filter or filters comprised of paper,woven fiberglass, nonwoven fiberglass, nonwoven polymers, and the likewhere the air filter or filters further comprise a method ofinactivating pathogens through the use of a compound or compounds thatare infused or coated into or onto the air filters.

The air filter or filters further comprise a polymer that is infused ormixed with a compound, such as a biocide or virucide, that willinactivate pathogens such as viruses and bacteria. The polymer may alsohave ablative or sacrificial characteristics where the surface of thepolymer may wear down with time, exposing a new fresh surface of thepolymer.

The ablative or sacrificial polymer may be an emulsion polymer comprisedof a polyvinyl acetate and acrylate backbone where the outer surface ofthe polymer will be worn away over time, exposing a new surface to theenvironment.

The sacrificial polymer may also be from the group of poly lactic acid(PLA), polycaprolactone (PCL), poly(lactic-co-glycolic acid) (PLGA),polyglycidyl methacrylate (PGMA), gelatin, polysaccharides, celluloseacetate, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, andpolyvinyl acetate copolymers. These polymers will degrade readily instandard temperature and pressure (STP) conditions such as theenvironment of an office building, school, or residence. In the case ofa residence, the residence may be temporary, such as a hotel or motel,or permanent, such as a house or apartment.

The virucide or biocide infused polymer may also be compounded suchthat, when coated onto the filter substrate, provides a continuoussupply of the virucide or virucide to the air that is flowing throughthe filter. One method of accomplishing this is to introduce a largeexcess of virucide or biocide into the polymer mixture such that thevirucide or biocide comes to the surface of the polymer through surfaceenergy, diffusion, capillary action, or other passive transportmechanisms.

The polymer that is coated on the filter system may also be of such anature that it is incompatible with the biocide or virucide such thatthe biocide or virucide, or any other material that would inactivate apathogen, is allowed to ooze or flow out of the polymer matrix. Thiswould be similar to a permanently oiled bearing where oil is infusedinto a sintered bearing and thus has long life lubrication as the oiloozes out of the sintered bearing. The polymer matrix may be a solid,solution, or emulsion type. The polymer may be borne by an organicsolvent or may be waterborne or maybe 100% solids.

The virucide or biocide may be a blend of virucides or biocides, eachhaving a different target area of pathogens.

Filter papers are used in many types of applications including airfilters for HVAC units and automobiles, coffee filters, fuel filters,chromatography separation, laboratory filters, and teabags to name a fewapplications. Porous air filters in HVAC systems may be manufactured ina manner to allow particles of different sizes to be trapped while othersizes may pass through the filter.

These filter papers have benefited from continued refinement andengineering to provide sustained and precise filtration methods forvarious materials.

Single-digit and fractional micron filtration is possible with manydifferent types of filter paper. The filter papers may also be treatedwith biocides and virucides to improve the protection from infectiousparticles that may be circulating in the air.

The coating of the filter substrate may be accomplished by a spray, dip,roll, print, or other transfer process whereby an ablative orsacrificial polymer is transferred to the surface of the specialtypaper. The ablative or sacrificial polymer may contain pathogeninactivating material such as a biocide or virucide. The roll processmay be a Mayer rod process or a gravure process.

A fiberglass base material may be utilized for the HVAC filter. Here,the ablative or sacrificial polymer with a biocide or a virucide, or anyother material that would inactivate a pathogen, is transferred to thefiberglass substrate. The fiberglass substrate may be woven or nonwoven.The ablative or sacrificial polymer will wear over time and exposed anew surface to the environment while it is coated on the fiberglasssubstrate.

The rating of the air filter may be of various levels. The AmericanSociety of Heating, Refrigerating and Air-Conditioning Engineers(ASHRAE) utilizes the standard as prescribed by ANSI/ASHRAE 52.2 for theMinimum Efficiency Reporting Value (MERV). A standard of MERV 13 orhigher has been prescribed by the Center for Disease Control (CDC).

There are various biocides and virucides available in the marketplacefor the inactivation of pathogens, including the SARS-CoV-2 virus thatis causing the Covid-19 pandemic. The biocides and virucides includematerials that incorporate chlorinated molecules such as quaternaryammonium salts with a chlorine molecule attached. Benzalkonium chlorideis an example of the material with a quaternary ammonium component and achlorine component. Many other types of biocides and virucides areavailable such as sodium hypochlorite (commonly known as bleach),hydrogen peroxide, and isopropyl alcohol. Other molecules include boron,iodine, and other chlorine containing molecules.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, like reference characters generally refer to the sameparts throughout the different views. In the following description,various embodiments of the present invention are described withreference to the following drawings, in which:

FIG. 1 illustrates an exemplary embodiment of an HVAC filter with avirucide infused coated fiberglass component;

FIG. 2 is a rendering of a HVAC filter with a virucide infused substrateand a holder for the substrate;

FIG. 3 is a chemical formula for benzalkonium chloride;

FIG. 4 is a chemical formula for poly(lactic-co-glycolic acid) (PLGA);

FIG. 5 is a chemical formula for polyglycidyl methacrylate (PGMA);

FIG. 6 is a table showing the MERV levels for air filters; and

FIG. 7 is a depiction of a furanose molecule with a phosphodiester bond.

DETAILED DESCRIPTION

Various embodiments described herein disclose a HVAC filters system thatis coated with a polymer where the polymer contains an agent forinactivating viruses. Specifically, in some examples, the virucide inthe polymer is used to inactivate the SARS-CoV-2 virus causing theCovid-19 pandemic.

The polymer may be an ablative or sacrificial polymer that will wearaway at the surface over time, thus exposing new material to theenvironment. The polymer may also be a material that's incompatible withthe inactivating agent such that the inactivating agent, a biocide orvirucide for example, will ooze out of the polymer for a long period oftime and thus inactivate viral particles when they impinge on the filtercoated with this polymeric configuration.

An ablative or sacrificial polymer may also be known as a sacrificialmaterial with the polymer subject to wear from environmental conditions.The ablation of a polymeric matrix may occur from thermal interaction,UV interaction, and other energetic, oxidating, or hydrogenatingenvironmental interactions. The ablative or sacrificial polymer may alsobe comprised of nano composites. The sacrificial polymer may wear awayand break down from environmental interactions.

The polymeric material, blended with a virucide or biocide, or anypathogen inactivating material, may be applied to the substrate byvarious means such as spraying, dipping, roll coating, and printing.Once the polymer is applied to the substrate, it may be cured or driedthrough various processes such as UV cure, drying in a heated oven, orair dried.

Test procedures, such as ISO-18184:2019, may be utilized to demonstratethe anti-viral capacity of a porous substrates. In accordance withISO-18184:2019, samples of a non-woven fiberglass with an MERV rating of13 treated with a polyvinyl acetate/acrylate copolymer infused withStepan BTC-885, a benzalkonium chloride containing mixture, were tested.The pathogen that was tested utilizing the ISO-18184:2019 standard wasthe SARS-CoV-2 virus, WA1 strain. The results of the testing show thatthe polymer and virucide infused non-woven fiberglass MERV 13 filterinactivated all of the SARS-CoV-2 WA1 virus in 15 minutes. The testresults are listed below in Table 1.

TABLE 1 Project Lot Test Contact Log₁₀ Protocol # No. No. Dilution Virustime Reduction IPAC.V.21.001 1123- Test N/A Severe Acute 15 ≥3.39 101Material Respirator Minutes Syndrome-Related Coronavirus 2 (SARS-CoV-2)(COVID-19 Virus)

The substrate that the polymer is coated onto may be composed of variousmaterials. The materials include both woven and nonwoven fiberglass,paper, nonwoven polymeric matrices, woven polymeric matrices, andsimilar support materials.

The polymeric coated substrate may then be fitted into a frame such thatit may easily be inserted into an HVAC system that currently acceptsregular types of filtration media.

FIG. 1 illustrates a type of HVAC filter 100 where a coated fiberglassmesh 101 has been incorporated into a paper frame. The fiberglass meshis coated with an ablative or sacrificial polymer 102 composed of apolyvinyl acetate and poly acrylate copolymer. The ablative orsacrificial polymer also contains a virucide, benzalkonium chloride 103.

FIG. 2 is a depiction of an air filter 200. The cross members 201 of theair filter frame 202 retain the filtration substrate 203. The filtrationsubstrate 203 may be a woven or non-woven substrate. The material of thefilter substrate 203 may be paper, fiberglass, or another suitablematerial. The filtration substrate 203 may be coated with a polymerwhere the polymer is infused with a virucide.

FIG. 3 depicts the benzalkonium chloride molecule 300, a stronganti-viral material.

FIG. 4 is the general chemical formula for poly(lactic-co-glycolic acid)(PLGA) 400. The poly(lactic-co-glycolic acid) (PLGA) polymer 400 is abiodegradable material that will ablate, wear away, and break down overtime.

FIG. 5 is the general chemical formula for polyglycidyl methacrylate(PGMA). The polyglycidyl methacrylate (PGMA) polymer 500 is abiodegradable material that will ablate, wear away, and break down overtime.

FIG. 6 is a chart showing the MERV levels for air filters as prescribedby ASHRAE. A MERV level of 13 or higher has been prescribed by the CDCfor air filtration in office buildings, schools, residences and otheroccupied interior spaces.

The air filter may also have a means for detecting viral material thatis impinged upon the filter. One such means for detecting the viralmaterial is the utilization of single-stranded DNA couple to amicrochip. When a material binds to the single-strand DNA, such as asingle-strand RNA that is characteristic of the SARS-CoV-2, a differencein electrical charge may be determined by the microchip attached to thesingle-strand DNA. This electrical difference in the microchip willallow for the determination of the attachment of a specific RNA strandto a detector. As more and more RNA strands attached to thesingle-strand DNA, more of an indication may be seen from the microchipattached to the DNA single-strand material. This will generate a signalthat will show the amount of single-stranded RNA attached to thesingle-strand DNA and thus identify both the viral load and the variantof the virus that is being detected. For instance, a single-stranded DNAwith the sequence that matches the single stranded RNA of the Deltavariant of the SARS-CoV-2 virus will bind with the viral RNA and cause achange in the electrical characteristics of the biosensor chip. Thiswill show not only that the Delta variant is present but also the amountof Delta variant that is present.

The single-stranded DNA (ssDNA) detector may also be utilized to checkthe efficacy of the virucide filter. An ssDNA detector may be mounteddownstream of a virucide infused filter such that the air passingthrough the virucide infused filter will subsequently come in contactwith the ssDNA detector. The ssDNA detector will then detect any viralload that is coming through the virucide infused filter, indicating thatthe efficacy of the virucide infused filter has been lessened and reportthis lower virucide all activity through an electronic communicationmeans.

The ssDNA detector may also be utilized as part of a system to indicateviral loads in a building or structure. The detectors may be placed invarious areas of the building or structure and connected into acommunications system, similar to a fire reporting communicationssystem, such that viral infections in a building or structure, such as ahospital, may be registered and recorded and dealt with appropriately.

An array of biosensors may be utilized to detect multiple types ofpathogens. For instance, biosensors set to detect the Alpha, Beta, andDelta variants of the SARS-CoV-2 virus would be utilized to detect notonly the viral load in a specific area but the type of virus that ispresent.

In another aspect of the biosensor, the biosensor may be coated with amaterial that simulates a cell membrane, such as a lipid monolayer orbilayer or polysaccharide layer. The simulated cell membrane may alsohave simulated receptors for the target pathogens, such as SARS-CoV-2viruses. The presence of this layer with simulate a cell membrane andfool the pathogen, such as a virus, to attaching and giving up its corenucleic acid for identification by the sensor.

Another aspect of this embodiment is the use of a specialized virucide,such as an enzyme like a RNA nuclease, to inactivate viral pathogens.The use of a Clustered Regularly Interspaced Short Palindromic Repeats(CRISPR)/CRISPR associated protein 13 (Cas13) may be utilized to cleaveRNA nucleic acid sequences. In one manner, RNA nucleases cleave thephosphodiester bonds of nucleic acids in the RNA, inactivating a singlestranded RNA virus (ssRNA) such as SARS-CoV-2. A phosphodiester bond isshown in FIG. 7. Cas13 targets RNA, not DNA. When it is activated by assRNA sequence that is complementary to its CRISPR-RNA (crRNA) spacer,the Cas13 releases nonspecific RNase activity and inactivates RNA in theCas13 vicinity without regards to the RNA sequence. Thus, Cas13 coupledwith crRNA forms a complex that may effectively inactivate ssRNA virusessuch as SARS-CoV-2.

Each numerical value presented herein is contemplated to represent aminimum value or a maximum value in a range for a correspondingparameter. Accordingly, when added to the claims, the numerical valueprovides express support for claiming the range, which may lie above orbelow the numerical value, in accordance with the teachings herein.Every value between the minimum value and the maximum value within eachnumerical range presented herein, is contemplated and expresslysupported herein, subject to the number of significant digits expressedin each particular range.

Having described herein illustrative embodiments of the presentinvention, persons of ordinary skill in the art will appreciate variousother features and advantages of the invention apart from thosespecifically described above. It should therefore be understood that theforegoing is only illustrative of the principles of the invention, andthat various modifications and additions, as well as all combinationsand permutations of the various elements and components recited herein,can be made by those skilled in the art without departing from thespirit and scope of the invention. Accordingly, the appended claimsshall not be limited by the particular features that have been shown anddescribed but shall be construed also to cover any obvious modificationsand equivalents thereof.

What is claimed is:
 1. A device for inactivating a pathogen in anenvironment, the device comprising: a substrate; a polymer coating thesubstrate; and a pathogen inactivating material infused within thepolymer, wherein, at a given time, a portion of the pathogeninactivating material is exposed to the environment, and wherein thedevice is configured to periodically or intermittently expose additionalpathogen inactivating material to the environment.
 2. The device ofclaim 1, wherein the substrate comprises a fiberglass material.
 3. Thedevice of claim 1, wherein the substrate comprises a paper material. 4.The device of claim 1, wherein the substrate comprises a woven material.5. The device of claim 1, wherein the substrate comprises a non-wovenmaterial.
 6. The device of claim 1, wherein the polymer comprises anablative polymer.
 7. The device of claim 1, wherein the polymercomprises a sacrificial polymer.
 8. The device of claim 1, wherein thepolymer comprises a copolymer.
 9. The device of claim 1, wherein thepathogen inactivating material comprises at least one of a virucide anda biocide.
 10. The device of claim 9, wherein the pathogen inactivatingmaterial comprises a virucide comprising at least one of: benzalkoniumchloride, quaternary ammonium salt, and an enzyme that targets a virus.11. The device of claim 1, wherein the pathogen inactivating material isof an amount such that it comes to the surface of the polymer through apassive transport mechanism.
 12. The device of claim 11, wherein thepassive transport mechanism comprises at least one of: surface energy,diffusion, and capillary action.
 13. The device of claim 1, wherein thedevice comprises an air filter.
 14. The device of claim 1, wherein thepolymer comprises at least one of: polylactic acid, polycaprolactone,poly(lactic-co-glycolic acid), polyglycidyl methacrylate, gelatin,polysaccharides, cellulose acetate, methyl cellulose, ethyl cellulose,hydroxyethyl cellulose, and polyvinyl acetate copolymer.
 15. The deviceof claim 14 where the pathogen inactivating material denatures theprotein component of the pathogen, rendering it inactive.
 16. The deviceof claim 14 where the pathogen inactivating material oxidizes thepathogen, rendering it inactive.
 17. The device of claim 14 where thepathogen inactivating material utilizes an enzymatic process toinactivate the pathogen.
 18. A method for inactivating a pathogen in anenvironment, the method comprising: coating a substrate with a polymerinfused with a pathogen inactiviating material, wherein the polymerinfused with the pathogen inactivating material is configured toperiodically or intermittently expose additional pathogen inactivatingmaterial to the environment.
 19. The method of claim 18, wherein thepolymer is a copolymer.
 20. The method of claim 18, wherein the pathogeninactivating material comprises a virucide comprising at least one of:benzalkonium chloride, quaternary ammonium salt, and an enzyme thattargets a virus.